Centrifugal fan



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F. PHELPS CENTRIFUGAL FAN Filed Aug. 9, 1915 WH'meSSeB:

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the shaft and the IGNon To L. c. n, 'or

application exea aman e, isis. semi in. eases.

Toallwhomtmay concern.' i

it own that l, FRANK Ps, a citieen of the United States, residing atLittle Roch, in the county of Pulaski and State of Arkansas, haveVinvented new and useful lmprovements in Centrifugal Fans, ot which the:ibllowing` is a specication, reference being had to the accompanyingdrawings, forming apart thereof.

The purpose ci this invention is to provide a 'simple and inexpensivetype ci construction for a centrifugal fan or blast wheel, suchconstruction beines especially designed to produce a wheel which whenadjusted to l a condition oi still balance will also be found to be insatisfactory running balance. llhe usual practice in building blastwheels is to connect the blade with the shaft by means of acomparatively heavy web which is either I formed as a casting or may bebuilt up from standard forms o? rolled steel,such as angles, plates, andthe like. 'Whether this web be a cartine or or" auch built-upconstruction its 1s not perfectly centered when niet mounted' u on theshaft, and the latter is therefore p aced on temporary bearings, and theblast wheel is balanced by either adding weights to the light parts orby drilling out seine oi the-metal in the heavier places until it willstand at rest at any point oi? rotative adjustment on 'its temporarybearings ln this condition the suin of the moments ot all the individualmasses which go to make up the wheel is equal to zero when such momentsare talrenwith respect to the cris 'of the shaft. `Likewise thealgebraic sum of the centrifugal forces or these various individualmasses will be zero; but with this usual class oil construction'thecenters of mass of the various parte of the wheel will not all lie inexactly the same plane perpendicular to the axis of rotation,-and thisis especially true if additional metal has been applied to the wheel atan point for'balancing urposes. The resu t is that although the w eelwill appear perfectly balanced so long as it stands at rest, thecentrifugal forces set up when the wheel-is revolved and actingedectively in diderent lanes corresponding to the planes in which diecenters of avity of the individual partshap en to he, willy produce oneor more coup es tending to cause rotation of the wheel and its shaft in.

planes containing the shaft axis. 0f course wheel are restrained 6, ofthe` other two angles, being against such movement by the hearingsbalanced couples thus set up tend to cause m which the shaft is mounted,but the unexcessive journal friction on said bearings,

and if they succeed in causing even a very slight bending of the shaftduring rotation the elastic ire-action of the shaft to such bending willset up a vibration of the parts which may be transmitted throughout theventire machine, and which is nearly always detrimental tothe lattere Toovercome these difficulties the present invention provides details ofconstruction hereinafter described and shown in' the drawings and whichare particularly set out in the appended claims.

in the drawings:

Figure l is anaxial section of a blast wheel and its mounting embodyingthis invention. Y

Figure 2 is a side elevation of the same with a part ci the casingbroken away to reveal 'the construction or the wheel itl.

Figure 3 is an enlarged detail section taken asindicated at line 3--3 onFigure 2.

AFigure d is an enlarged detail section tahen as indicated at line 4 4on Figure 2.

secured a thin metal dish, 5, which consti-l tutes the web of the wheel.The disk, 5', is cut exactly circular with a central opening toaccommodate the hub, 2, and may be somewhat lightened by additionalaper-v tures, 5a, punched out ci its area immediately surrounding thehub, 2. Near the eriphery of the dish, 5, are secured the pan blades, 6,and preferably these are arranged in symmetrical fashion projectin frommth faces of the disk, as indicate in the detail section of Figure 3.

Each blade unit is shown as composed of four parts, namely, two anglesdi osed with their shorter length, 6, oppose and secured together byrivets, 7, fastened to the disk, 5, and with their longer lengths,

t", extending oppositcly atl rlght angles from the disk, 5. The bladesthus formed of the angles', 6, are reinforced by additional angles whoseopposing` lengths, 8a, are connected by rivets, 9, passing through theweb 5, while their other lengths, 8b, are brace against and riveted tothe respective parte y hel los' by rivets, l0. lt will be understoodthat the angles of which the blades are thus composed may readily beformed as stamplng of sheet metal so as to be absolutely uniform inshape and Weight, so that with the vveb, 5, composed of a homogeneoussheet of metal there is little, if anything, in the construction tocause an imperfect balance in the wheel, and so that When itis firstplaced in temporary bearings it will be found to be very nearly in acondition of still balance. Slight inequalities in the heads of therivets, 7, 9 and 10, or slight imperfections in the stock of Which theblade is composed may, however, require that a little Work be done onthe Wheel to bring it into perfectly balanced condition. Any suchimperfections or other slight modiications of the parts to oil-set them,is likely however to result in the distribution of mass centers intomore than one transairial plane, so that when the wheel is rotatedrapidly there may be set up couples of forces tending to throvv theshaft out of alignment as previously explained. Under this conditionhowever slight, the mass centers of some of the elen ments composing thewheel are not quite in the mid-plane ci the web, 5, but the centril ugalforce acting at any one ol these misplaced mass centers being opposed bythe radial tension in the web, produces a small resultant force actingtransversely of said web and tending to move the individual mass centerin such transverse direction to bring thet centrifugal force and theopposing tension into a common line of action. Nowthe web, 5, beingcomposed of sheet metal and being rendered especially flexible by virtueof the removal of a very con siderable portion of the material atapertures, 5a, is adapted to yield to this small transverse force toallow the misplaced mass to assume a position in a common plane with themajority of the individual mass centers of the Wheel; in other Words,any of the blade units Whose mass is not quite symmetrically distributedwith respect to the web, 5, is ermitted to shift its position andthereby shiftits center of mass in a direction transverseto the web, 5,and approximately parallel to the axis of the Wheel,-such shifting beingpermitted by virtue of the flexibility of the disk, 5', by which theblades are carried. Thus While the Wheel is revolving with greatvelocity the dislr, 5, may be slightly bent or buckled out oi' its normal plane at certain parts, but the result Will be an elimination of allcouples tending to displace the shalt axis or to exert bending strainsupon the shalt.

rlhe casing for this wheel is quite simple in construction beingcomposed of two side plates, il, both centrally apertured and havingtheir apertures reinforced by annular members, l2, which are Z-shaped incross section. Near the peripheral outline'ol each plate, 11, butslightly set in from such edge there is riveted to the plate a strip,13, which thus serves as a lian e or shoulder for lodgment of the periperal casing wall, lll, which is merely a strip of sheet metal of uniformWidth laid in position upon the flange members, `13, and held in placeby the tie bolts, 15, which transversely connect the side plates, 11,and cross between them just outside the Wall, 14. As indicated in Figure2, the plates, 11, are cut to form the usual tangent discharge openingat 16, the peripheral Wall, 14, terminating at opposite sides of saidopening.

Journal bearings for the shaft, l, are supported in a frame. l?, and theblast wheel casing is also supported on `this traine, 17, partly bymeans of three bolts,` 18, passing through a central plate, 19, whichtrictionally engages the web of the annular niembei212. An additionalclamp is provided in the form of a. hook bolt, 20, at the upper portionot said plate which also maintains rictional engagement between theplate and member, 12. rl-he nut of this bolt, 20, is accessible byreaching through one of the apertures, 5a, of the web, 5, it beingunderstood that 'the central aperture in the side plate, ll, which isbeyond the end ot the shalt, l, is lett open to serve as an intake forthe. air supply to the blast Wheel. Thus, by virtue oll the Whollyirictional engagement between the casing and the plate, 19. of frame,17, the casing may be rotatively adjusted to bring its discharge mouth,16, at any angle, upon merely loosening the bolts, 18 and 20.

Since the blade portions, 6b, of the fan wheel are disposed in planessubstantially radial to the axis of the Wheel it will be seen that the`wheel may be operated by rotation in either direction. rl`he sideplates, 11. et the casing are therefore exactly similar in constructionso that by removing the` bolts` 18 and 20. the friction plate, 19, maybe completely disengaged from the Z-bar, 12. of the side Wall, il,permitting the casing to be taken apart and reassembled with the plate.19, in the aperture of the other side wall, 11. rl`hus without anydifferences of construction the fans built according to this design areadapted to be operated either right-handed or left-handed. Furthermore,the design is so simple that the parts can be shipped in knock-down formand readily assembled by any ordinary mechanic. rThe first element toshow signs of Wear is usually the peripheral Wall, 1.4i, but this isvery easily renewed by merely removing the bolts, 15, replacing theWall, 14, with a new strip of sheet metal and again clamping the bolts.15. into position.

The journal bearings, 21, are shown as lined with the usual bearingmetal, 22, and

provided with ring oilers 23, whose operation is Well understood. Bothjournal boxes are provided with oil filler tubes, 24, and' are formedwith oil chambers, 25. surrounding the journal supports, 21. Thesechambers, however, are connected by a channel. 26, extending through theframe, 17, so that whenever oil is introduced in either of theY fillertubes, 24, it is supplied to both bearings rising to the same level inboth oil chambers, 25, by virtue of the connection, 26. The connection,26. is provided with a discharge openingand a plug, 27. therefor, to beused for draining oft1 the entire supply of o il if desired. A pulley,28,

` is shown. fixed to the shaft, 1. between the i journal bearings, 21.but it will be understood that any suitable form of power transmissionmay be employed for driving the wheel.

I claim:

1. In a centrifugal fan, a casing comprising side plates havingoutwardly facing shoulders on their proximate sides, a peripheral wallmember mounted upon said shoulders and spacing the side plates apart,and tie members extending from oneslde plate to the other just outsidesuch periph-l eral Wall and holding the latter in place on the saidshouders.

2. In a centrifugal fan, a casin comprising side plates having outwar lyfacing shoulders on their proximate sides, a peripheral wall membermounted upon said shoulders and spacing the side lates apart, andremovable tie bolts extending through said side plates justv outside theperipheral wall for disengageably holding the plates in position.

3. In the combination of a fan wheel, a shaft and journal bearingstherefor, to gether with a casing and a standard adapted to support saidbearings and said easing, the casing wall having a central aperture, aplate in the easing overlapping` the edge of said aperture, and clampinbolts extending from the standard throng the plate and within saidcentral aperture for rictionally holding the casing to the standard.-

4. In the combination defined in claim 3, the aperture of the casingbeing reinforced by a circular member having a flange transverse to thecasing wall, and the plate being fitted within said flange to center thecasing for rotative adjustment on the standard.

In testimony whereof I have hereunto set

